Thermostat



FIG. 1 is a top, left, front perspective view of a thermostat, showing my new design;

FIG. 2 is a right side elevational view thereof;

FIG. 3 is a left side elevational view thereof; and

FIG. 4 is a front elevational view thereof. The rear is substantially flat, plain and conventional. 

The ornamental design for a thermostat, as shown and described. 